The research in this study proposes to charactrize the uptake of enzymes by human fibroblasts in culture and in perfused rat kidneys as models for enzyme therapy. Trihexosylceramide-alpha-galactosidase A will be purified and characterized from human placenta and its uptake will be studied in skin fibroblasts from patients with Fabry's disease and in perfused rat kidneys. Kinetics of enzyme uptake, mechanism of enzyme uptake, stability of the engulfed enzyme and intracellular site of enzyme uptake will be determined. Modification of the carbohydrate of the glycoprotein and competition for uptake by other glycoproteins and carbohydrates will be employed to determine the structure of the recognition marker that is necessary for rapid uptake of the enzyme. The therapeutic value of the enzyme replacement will be followed by the disappearance of glycolipid in the lysosomes of the fibroblasts. The long-term objective of the proposed research is to characterize the uptake of enzymes into cells and into lysosomes in order to facilitate enzyme therapy in lysosomal storage diseases.